    body {
      font: 12px/1.5 Helvetica;
      color: chocolate;
    }

    div {
      font-size: 18px;
    }

    p {
      color: royalblue;
    }

    table {
      width: 500px;
    }

    table,
    th,
    td {
      text-align: center;
      font: 16px 'Microsoft Yahei';
      color: #000;
      border: 1px solid gray;
      /* 相邻边框合并 */
      border-collapse: collapse;
    }

    th {
      height: 35px;
      font-weight: 900;
    }

    .test {
      /* 最终还是执行 ∞ 级 */
      color: burlywood !important;
    }

    #test {
      color: cadetblue;
    }

    /* 继承至body的权重为0，元素选择器为1 */
    h3 {
      font-size: 21px;
      font-weight: 700;
      color: #000;
    }

    /* 权重的叠加 */
    li {
      color: red;
    }

    /* [li] 为 [0,0,0,1] 而 [ul li] 叠加为 [0,0,0,2] */
    ul li {
      color: yellow;
    }

    /* [.weight li] 叠加为 [0,0,1,1] */
    .weight li {
      color: palevioletred;
    }

    /* [*:hover] 叠加为 [0,0,0,2] */
    *:hover {
      color: rgb(0, 255, 21);
    }

    /* 权重练习 */
    .train li {
      color: pink;
    }

    /* 权重低了，不会生效！ */
    .red-bold {
       color: red;
      font-weight: 700;
    }

    li:first-child {
      color: red;
      font-weight: 700;
    }

    li:nth-child(2) {
      color: green;
    }
    
    li:last-child {
      color: blue;
    }